1. Field of the Invention
The present invention is directed to the use of thermophilic (heat loving) bacteria for effecting the efficient aerobic decomposition of animal and other solid organic wastes to produce a pasteurized, organic fertilizer, mulch, and/or an animal feed ingredient.
Broadly speaking, the use of thermophilic bacteria for effecting the aerobic decomposition of organic wastes is not new.
The present invention is directed to an improved, highly efficient method of processing organic waste, and in particular animal manure, by providing an ideal environment for enhancing the growth of thermophilic bacteria in the waste product being subjected to aerobic decomposition.
The process of the present invention does not run afoul of the ecological standards. The by-products produced during the aerobic decomposition are carbon dioxide and water, and the final product is free of odor. Practice of the process does not produce an air or water pollution problem.
2. Description of the Prior Art
In an article in the Oct, 1972 issue of Feedlot Management magazine, entitled "Manure Is Food For Protein" at pages 18-20, a process developed by General Electric Company is described wherein raw cattle manure is converted into a pasteurized protein powder animal feed supplement. In the General Electric process cattle manure is fed to a particular strain of thermophilic bacteria, the bacteria being mixed with the manure and water in a series of fermentation tanks, the contents of which are maintained at 130.degree.-140.degree. F.
U.S. Pat. No. 2,954,285 discloses the use of an elongate, rotatable drum having three zones in which waste materials containing organic constituents are subjected to aerobic thermophilic fermentation. The organic constituents are continuously advanced in the drum through a preheating zone, a main fermentation zone and a drying zone. Air is introduced into the fermenting mass, and in some instances, water is also added to the material. The reference teaches that pasteurization occurs when the temperature of the mass rises to 60.degree.-70.degree. C.
U.S. Pat. No. 3,438,470 discloses a composting conveyor, and in Col. 3, lines 30-43, it is stated that digestion of organic material occurs in two phases, "a first phase of mesophilic digestion in the range of about 110.degree. for a 24 hour period, then thermophilic digestion at about 140.degree. F. for a further 24 hour period followed by a sterilization period of approximately 165.degree. F. for a 48 hour period." The digesting process "is helped by the introduction of air at the bottom of the tank" and by the addition of water to the material being processed.
U.S. Pat. No. 3,285,732 discloses the method of effecting the aerobic decomposition of organic material by continuously maintaining the contents of a composting vessel in the thermophilic temperature range and of intermixing undecomposed organic material at ambient temperature with the decomposing mass so that the newly added undecomposed material is thoroughly intermixed with the decomposing mass. Air is supplied to the contents of the vessel at a rate such that the "exhaust gas" from the decomposing mass contains residual oxygen.
U.S. Pat. No. 2,474,833 discloses a method for making organic fertilizer from organic waste by the propogation of aerobic bacteria while continuously forcing air through a mass of decomposing organic material housed within a vertical tank. The contents of the tank are agitated and the spent air is continuously withdrawn from the mass at vertically spaced intervals of the tank.
U.S. Pat. Nos. 3,010,801 and 3,138,448 disclose, respectively, apparatus and a method for aerobic decomposition of organic wastes wherein controlled quantities of oxygen are injected into a decomposing mass and wherein the exhaust gas from the decomposing mass is utilized to determine the amount of oxygen-containing-gas required to effectively facilitate the thermophilic decomposition of the organic waste products.
U.S. Pat. No. 2,947,619 discloses a process for manufacturing compost composed of fermented organic waste material while in a windrow, the particles of which are sprayed with water for facilitating the aerobic fermentation of the contents of the pile until such time as the moisture content is reduced to about 35% after which the product is turned or worked and tossed into the air whereby to fall, by gravity, to form another porous windrow pile, said technique being repeated until such time as the aerobic fermentation is substantially complete.
U.S. Pat. No. 3,114,622 discloses a method of utilizing thermophilic bacteria for effecting decomposition of organic waste material in solid flowable form by providing the organic material in two horizontal beds of substantially constant depth, wherein fresh undecomposed material is added in small increments throughout the entirety of one bed and of removing sufficient digested material to maintain the bed depth constant.
U.S. Pat. No. 2,285,834 discloses a process for the treatment of organic matter by fermentation utilizing thermophilic bacteria until such time as the entire mass has been converted into a substantially dry, humus fertilizer having the appearance of leaf mold.
U.S. Pat. No. 2,878,112 discloses a method for composting manure by providing controlled conditions of air, moisture and temperature which are conducive to the growth of bacteria wherein the organic material to be composed is maintained in a vertical column from the bottom of which column some of the manure is withdrawn and returned to the top of the column whereby each manure particle in the column will eventually migrate from the top to the bottom of the column. The contents of the column are continuously aereated and exposed to a controlled current of moist, warm air.
U.S. Pat. No. 3,294,491 discloses an apparatus to be used in composting organic waste products and on page 3, lines 46-52, it is stated that "during the mesophilic phase of digestion the temperature of air discharged from the pots 46 may be regulated to maintain 110.degree. F. temperature within the mass of organic material 44. Likewise, the thermophilic and sterilizing phases may be regulated as to the respective temperature of 140.degree. and 165.degree.."
Each of U.S. Pat. Nos. 3,438,740; 3,294,491; 3,323,896; 3,385,687 and 3,451,791 either disclose or refer to the process of subjecting organic material to a mesophilic phase of digestion at 110.degree. F. temperature after which it is subjected to thermophilic temperature of 140.degree. F. and thereafter to sterilizing temperatures of 165.degree. F.